virtualbox.org

VirtualBox is locking up when I try to add the Extension Pack.

I have uninstalled VirtualBox, Re-booted, Cleaned temp files, ran CCleaner
I installed VirtualBox 4.2.12-93733 by selecting Run As Administrator.
I get a message saying "Failed to create the VirtualBox COM object."
I change VirtualBox.exe to run in compatibility mode "Windows XP sp3"
I start VirtualBox.exe by selecting Run As Administrator.
In File, Preferences, Extensions, I select the small down arrow to the right of Version.
I select the file:
Oracle_VM_VirtualBox_Extension_Pack-4.3.12-93733.vbox-extpack

The settings box and the Oracle VM VirtualBox Manager freezes up.
No buttons work.

Host: Win7
Antivirus: None
Guest: XP

I tried installing it from a bat file. I ran the bat file with Run As Administrator:
C:\Dnload\VirtualBoxConfigure>C:\Programs\VirtualBox\VBoxManage.exe extpack install "C:\Dnload\VirtualBoxConfigure\Oracle_VM_VirtualBox_Extension_Pack-4.3.12-93733.vbox-extpack"
VBoxManage.exe: error: Failed to create the VirtualBox object!
VBoxManage.exe: error: Code E_INVALIDARG (0x80070057) - One or more arguments are invalid (extended info not available)
VBoxManage.exe: error: Most likely, the VirtualBox COM server is not running or
failed to start.

How can I get the Extension Pack installed?

Thank you,

Docfxit